 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.core.runtime;

 /**
  * An adapter manager maintains a registry of adapter factories. Clients
  * directly invoke methods on an adapter manager to register and unregister
  * adapters. All adaptable objects (that is, objects that implement the <code>IAdaptable</code>
  * interface) funnel <code>IAdaptable.getAdapter</code> invocations to their
  * adapter manager's <code>IAdapterManger.getAdapter</code> method. The
  * adapter manager then forwards this request unmodified to the <code>IAdapterFactory.getAdapter</code>
  * method on one of the registered adapter factories.
  * <p>
  * Adapter factories can be registered programmatically using the <code>registerAdapters</code>
  * method. Alternatively, they can be registered declaratively using the
  * <code>org.eclipse.core.runtime.adapters</code> extension point. Factories registered
  * with this extension point will not be able to provide adapters until their
  * corresponding plugin has been activated.
  * <p>
  * The following code snippet shows how one might register an adapter of type
  * <code>com.example.acme.Sticky</code> on resources in the workspace.
  * <p>
  *
  * <pre>
  * IAdapterFactory pr = new IAdapterFactory() {
  * public Class[] getAdapterList() {
  * return new Class[] { com.example.acme.Sticky.class };
  * }
  * public Object getAdapter(Object adaptableObject, Class adapterType) {
  * IResource res = (IResource) adaptableObject;
  * QualifiedName key = new QualifiedName(&quot;com.example.acme&quot;, &quot;sticky-note&quot;);
  * try {
  * com.example.acme.Sticky v = (com.example.acme.Sticky) res.getSessionProperty(key);
  * if (v == null) {
  * v = new com.example.acme.Sticky();
  * res.setSessionProperty(key, v);
  * }
  * } catch (CoreException e) {
  * // unable to access session property - ignore
  * }
  * return v;
  * }
  * }
  * Platform.getAdapterManager().registerAdapters(pr, IResource.class);
  * </pre>
  *
  * </p><p>
  * This interface can be used without OSGi running.
  * </p><p>
  * This interface is not intended to be implemented by clients.
  * </p>
  * @see IAdaptable
  * @see IAdapterFactory
  */
 public interface IAdapterManager {

     /**
      * This value can be returned to indicate that no applicable adapter factory
      * was found.
      * @since org.eclipse.equinox.common 3.3
      */
     public static final int NONE = 0;

     /**
      * This value can be returned to indicate that an adapter factory was found,
      * but has not been loaded.
      * @since org.eclipse.equinox.common 3.3
      */
     public static final int NOT_LOADED = 1;

     /**
      * This value can be returned to indicate that an adapter factory is loaded.
      * @since org.eclipse.equinox.common 3.3
      */
     public static final int LOADED = 2;

     /**
      * Returns the types that can be obtained by converting <code>adaptableClass</code>
      * via this manager. Converting means that subsequent calls to <code>getAdapter()</code>
      * or <code>loadAdapter()</code> could result in an adapted object.
      * <p>
      * Note that the returned types do not guarantee that
      * a subsequent call to <code>getAdapter</code> with the same type as an argument
      * will return a non-null result. If the factory's plug-in has not yet been
      * loaded, or if the factory itself returns <code>null</code>, then
      * <code>getAdapter</code> will still return <code>null</code>.
      * </p>
      * @param adaptableClass the adaptable class being queried
      * @return an array of type names that can be obtained by converting
      * <code>adaptableClass</code> via this manager. An empty array
      * is returned if there are none.
      * @since 3.1
      */
     public String [] computeAdapterTypes(Class adaptableClass);

     /**
      * Returns the class search order for a given class. The search order from a
      * class with the definition <br>
      * <code>class X extends Y implements A, B</code><br>
      * is as follows:
      * <ul>
      * <li>the target's class: X
      * <li>X's superclasses in order to <code>Object</code>
      * <li>a breadth-first traversal of the target class's interfaces in the
      * order returned by <code>getInterfaces</code> (in the example, A and its
      * superinterfaces then B and its superinterfaces) </li>
      * </ul>
      *
      * @param clazz the class for which to return the class order.
      * @return the class search order for the given class. The returned
      * search order will minimally contain the target class.
      * @since 3.1
      */
     public Class [] computeClassOrder(Class clazz);

     /**
      * Returns an object which is an instance of the given class associated
      * with the given object. Returns <code>null</code> if no such object can
      * be found.
      * <p>
      * Note that this method will never cause plug-ins to be loaded. If the
      * only suitable factory is not yet loaded, this method will return <code>null</code>.
      *
      * @param adaptable the adaptable object being queried (usually an instance
      * of <code>IAdaptable</code>)
      * @param adapterType the type of adapter to look up
      * @return an object castable to the given adapter type, or <code>null</code>
      * if the given adaptable object does not have an available adapter of the
      * given type
      */
     public Object getAdapter(Object adaptable, Class adapterType);

     /**
      * Returns an object which is an instance of the given class name associated
      * with the given object. Returns <code>null</code> if no such object can
      * be found.
      * <p>
      * Note that this method will never cause plug-ins to be loaded. If the
      * only suitable factory is not yet loaded, this method will return <code>null</code>.
      * If activation of the plug-in providing the factory is required, use the
      * <code>loadAdapter</code> method instead.
      *
      * @param adaptable the adaptable object being queried (usually an instance
      * of <code>IAdaptable</code>)
      * @param adapterTypeName the fully qualified name of the type of adapter to look up
      * @return an object castable to the given adapter type, or <code>null</code>
      * if the given adaptable object does not have an available adapter of the
      * given type
      * @since 3.0
      */
     public Object getAdapter(Object adaptable, String adapterTypeName);

     /**
      * Returns whether there is an adapter factory registered that may be able
      * to convert <code>adaptable</code> to an object of type <code>adapterTypeName</code>.
      * <p>
      * Note that a return value of <code>true</code> does not guarantee that
      * a subsequent call to <code>getAdapter</code> with the same arguments
      * will return a non-null result. If the factory's plug-in has not yet been
      * loaded, or if the factory itself returns <code>null</code>, then
      * <code>getAdapter</code> will still return <code>null</code>.
      *
      * @param adaptable the adaptable object being queried (usually an instance
      * of <code>IAdaptable</code>)
      * @param adapterTypeName the fully qualified class name of an adapter to
      * look up
      * @return <code>true</code> if there is an adapter factory that claims
      * it can convert <code>adaptable</code> to an object of type <code>adapterType</code>,
      * and <code>false</code> otherwise.
      * @since 3.0
      */
     public boolean hasAdapter(Object adaptable, String adapterTypeName);

     /**
      * Returns a status of an adapter factory registered that may be able
      * to convert <code>adaptable</code> to an object of type <code>adapterTypeName</code>.
      * <p>
      * One of the following values can be returned:<ul>
      * <li>{@link org.eclipse.core.runtime.IAdapterManager#NONE} if no applicable adapter factory was found;</li>
      * <li>{@link org.eclipse.core.runtime.IAdapterManager#NOT_LOADED} if an adapter factory was found, but has not been loaded;</li>
      * <li>{@link org.eclipse.core.runtime.IAdapterManager#LOADED} if an adapter factory was found, and it is loaded.</li>
      * </ul></p>
      * @param adaptable the adaptable object being queried (usually an instance
      * of <code>IAdaptable</code>)
      * @param adapterTypeName the fully qualified class name of an adapter to
      * look up
      * @return a status of the adapter
      * @since org.eclipse.equinox.common 3.3
      */
     public int queryAdapter(Object adaptable, String adapterTypeName);

     /**
      * Returns an object that is an instance of the given class name associated
      * with the given object. Returns <code>null</code> if no such object can
      * be found.
      * <p>
      * Note that unlike the <code>getAdapter</code> methods, this method
      * will cause the plug-in that contributes the adapter factory to be loaded
      * if necessary. As such, this method should be used judiciously, in order
      * to avoid unnecessary plug-in activations. Most clients should avoid
      * activation by using <code>getAdapter</code> instead.
      *
      * @param adaptable the adaptable object being queried (usually an instance
      * of <code>IAdaptable</code>)
      * @param adapterTypeName the fully qualified name of the type of adapter to look up
      * @return an object castable to the given adapter type, or <code>null</code>
      * if the given adaptable object does not have an available adapter of the
      * given type
      * @since 3.0
      */
     public Object loadAdapter(Object adaptable, String adapterTypeName);

     /**
      * Registers the given adapter factory as extending objects of the given
      * type.
      * <p>
      * If the type being extended is a class, the given factory's adapters are
      * available on instances of that class and any of its subclasses. If it is
      * an interface, the adapters are available to all classes that directly or
      * indirectly implement that interface.
      * </p>
      *
      * @param factory the adapter factory
      * @param adaptable the type being extended
      * @see #unregisterAdapters(IAdapterFactory)
      * @see #unregisterAdapters(IAdapterFactory, Class)
      */
     public void registerAdapters(IAdapterFactory factory, Class adaptable);

     /**
      * Removes the given adapter factory completely from the list of registered
      * factories. Equivalent to calling <code>unregisterAdapters(IAdapterFactory,Class)</code>
      * on all classes against which it had been explicitly registered. Does
      * nothing if the given factory is not currently registered.
      *
      * @param factory the adapter factory to remove
      * @see #registerAdapters(IAdapterFactory, Class)
      */
     public void unregisterAdapters(IAdapterFactory factory);

     /**
      * Removes the given adapter factory from the list of factories registered
      * as extending the given class. Does nothing if the given factory and type
      * combination is not registered.
      *
      * @param factory the adapter factory to remove
      * @param adaptable one of the types against which the given factory is
      * registered
      * @see #registerAdapters(IAdapterFactory, Class)
      */
     public void unregisterAdapters(IAdapterFactory factory, Class adaptable);
 }

